The use of gels, which usually contain water, as intermediate layers in laminated glass constructions is known. Alkali metal silicate gels or gels based on organic polymers are in general used for this purpose. The former have the disadvantage that, because of the alkali metal content, in the event of a fire they promote melting through or flowing away of the glass at high temperatures, and the latter have the disadvantage that they burn after evaporation of the water and leave behind the glass unprotected.
Intumescence carriers, including those in solid form, which comprises ammonium and/or amine salts of acid phosphates of metals of group 2 and/or 3 of the periodic system of the elements are the subject matter of a previous patent application filed by the Applicant Company. In contrast, firepfoofing gels and precursors thereof which are of relatively low viscosity, that is to say capable of flow, at about room temperature and form transparent gels at a higher temperature have now been found.